Criminal Charges Pending Against Boston Bombing Suspect

U.S. authorities are preparing criminal charges against the Boston Marathon bombing suspect and could file them against him on Monday.

The exact charges to be filed against Dzhokhar Tsarnaev remain uncertain. Some U.S. legal analysts say he could face federal terrorism charges in the deaths of three victims who were killed in twin explosions near the finish line of last week's race, as well as a murder charge brought by Massachusetts officials in the shooting death of a university policeman in the violence-filled hours before his capture Friday night.

Meanwhile, the 19-year-old Tsarnaev remained hospitalized under guard, lapsing in and out of consciousness and unable to speak to investigators. He is suffering a gunshot wound to his throat, although it is unclear whether it came from a shootout with police or was self-inflicted. However, Tsarnaev has been answering some questions in writing.

After Boston's virtual lockdown on Friday during the manhunt for Tsarnaev, the city returned to some sense of normalcy Monday. Commuters filled major highways leading into city, children walked to schools and businesses opened their doors on the first day of the work week.

Boston, a large, major city in the northeastern U.S., was set to hold a moment of silence Monday at 2:50 p.m. local time to mark the passing of a week since the deadly explosions. Bells are scheduled to ring throughout Boston and in other parts of Massachusetts to mark the solemn occasion.

A private funeral was set for one of the bomb victims, a restaurant catering manager, as well as a memorial service for a university graduate student killed in the blasts.

On Sunday, Boston's top police official said investigators believe the two brothers suspected in the bombings, Dzhokhar Tsarnaev and his older brother Tamerlan, were planning other attacks.

Boston Police Commissioner Ed Davis said authorities found a cache of homemade explosives after the gun battle between police and the Tsarnaev brothers. Davis said the scene was littered with unexploded bombs, and police found one improvised explosive device in the vehicle the brothers are accused of stealing.

The elder brother, 26-year-old Tamerlan, died in the shootout Thursday, while the younger Dzhokhar escaped, only to be captured alive hiding in a boat parked in the back yard of a suburban Boston resident.

The two suspects are ethnic Chechen immigrants who came to the United States as boys. Authorities have given no indication as to what motivated the brothers. So far, authorities say they do not believe the brothers were affiliated with a larger terrorist network and that they had acted alone.

Travel records show that last year Tamerlan Tsarnaev spent six months in Dagestan and Chechnya, predominantly Muslim republics in the north Caucasus region of Russia with active militant separatist movements.

U.S. investigators interviewed him in early 2011 at the request of "a foreign government," acknowledged by U.S. officials to be Russia.

A U.S. FBI statement late Friday indicated the request said Tamerlan had become a follower of radical Islam "and that he had changed drastically since 2010 as he prepared to leave the United States for travel to the country's region to join unspecified underground groups."